Advances in cardiac surgery have enabled open heart and less-invasive methods for a wide variety of cardiac surgical procedures such as heart valve replacements or repairs. In many of these procedures, it is often necessary to retract tissue and bones in order to provide access to a surgical site. For example, in a sternotomy, where a vertical inline incision is made along the sternum, after which the sternum is divided or “cracked”, a large sternum retractor, such as retractor 30 of FIG. 1A, is used to force the cracked sternum apart, providing access to the heart 32. This type of sternum retractor 30 has jaws 34, 36 which open in a single plane. While a sternotomy provides excellent access to the heart 32, the procedure is highly invasive and is associated with a high degree of post-operative pain and long recovery times for patients.
With advances in minimally invasive cardiac approaches, surgeons have been able move away from sternotomies for many procedures. For example, one favored approach to access the heart is to use a right anterior thoracotomy (a much smaller incision in the chest wall). The thoracotomy is often made between two adjacent ribs, and it is often necessary to spread those ribs apart to create an access window for the surgery. This can be done with a smaller version of the single plane style retractor shown in FIG. 1A, or, in some cases, with hand-manipulated retractors 38, 40 such as are shown in FIG. 1B. Hand manipulated retractors 38, 40 require an extra person's pair of hands, which may crowd the operating area around the patient. Hand retractors 38, 40 are also difficult to maintain in an open position over an extended period of time due. Therefore, a mechanical rib retractor may be favored over the hand-retractors, since it provides steady sustained retraction and may reduce operator fatigue and even the need for an additional person in the operating room.
Unfortunately, traditional thoracotomies, made through adjacent ribs, often do not provide enough access for certain types of cardiac procedures. While surgical instruments such as fiber optic scopes, forceps, cutting tools, and suturing tools may fit relatively well through a thoracotomy between adjacent ribs, replacement heart valves and their holders often do not (even when the adjacent ribs are spread apart with existing retractors). As a result, for many cardiac procedures, the thoracotomy often requires resection or removal of ribs in order to provide additional room for larger items, such as a replacement heart valve. While transection with or without reattachment of a rib can be less traumatic than a sternotomy, it would still be desirable to avoid excessive rib mobilization in order to provide less post-operative pain and quicker recovery times for patients.
Several other types of rib retractors have been developed in order to try to provide a larger access space between adjacent ribs. Before describing these retractors, however, it is helpful to consider different orientations of human anatomy so that the motion and operation of the refractors can be compared and contrasted according to how they move relative to the anatomy. Accordingly, human body 42 location references are illustrated in FIG. 2. Three anatomical planes are illustrated, dividing the body 42 into different sectors. The sagittal plane 44 divides into a left portion 46 and a right portion 48. The coronal plane 50 divides into an anterior (front) portion 52 and a posterior (back) portion 54. The transverse plane 56 divides into an upper portion 58 and a lower portion 60. A direction towards the head 62 may generally be referred to as a cephalad direction, while a direction towards the lower end of the spine 64 may generally be referred to as a caudad direction. Therefore, an axis running approximately in a direction from the head towards the lower portion of the body could be referred to as a substantially cephalad-caudal axis. Similarly, an axis running approximately in a direction from the back of the body to the front of the body could be referred to as a substantially anterior-posterior axis.
U.S. Pat. No. 5,865,731 discloses a surgical refractor that “is able to form an oblique tunnel-like opening at an incision site wherein, in addition to spreading the sides of the site incision substantially parallel to the contour of the patient's body, the ['731] surgical retractor additionally spreads the incision sides so that one side is depressed toward the patient and the other is directed outwardly from the patient.” However, the rotational or offset positions for the grips must be predetermined before use since only one amount of anterior-posterior movement is possible during use. Furthermore, there is no spreading of the ribs in a cephalad-caudal direction without also having anterior-posterior separation. This may be undesirable since the additional anterior-posterior separation (and its resultant stress on the ribs) may not be needed for the entire duration of an operation.
U.S. Pat. No. 6,159,231 discloses a retractor having two racks movably attached at a nonlinear angle. When the first rack section is horizontally disposed, the other rack section is angled relative to the horizontal plane. The refractor may be ratcheted apart to spread adjacent ribs in a cephalad-caudal direction. One end of the retractor may also be lifted to spread the ribs in an anterior-posterior direction. The lifted end, however, must be held by hand or attached to a cable anchored to a support over the patient in order to maintain the anterior-posterior separation. This either requires additional personnel in the operating room, or modifications to the operating table/ceiling, neither of which is desirable as the additional equipment may get in the surgeon's way.
European Patent 792,620 discloses several embodiments of a rib retractor having adjustments to spread adjacent ribs in a cephalad-caudal direction. These retractors also have an adjustment to lift one rib relative to the other by contacting the patient somewhere else besides the ribs to create a fulcrum point for lifting leverage. Unfortunately, this additional contact point can cause additional bruising for the patient and may be difficult to use on obese patients.
European Patent 792,620 also discloses a version of a rib retractor where the spreader is attached to the operating table or to some platform which can be slid beneath the patient. This rib retractor has adjustments for both anterior-posterior separation as well as cephalad-caudal separation. While this embodiment alleviates the unnecessary bruising of previous models, its external anchoring system is also complex, cumbersome, and difficult to reposition.
European Patent 792,620 further discloses an embodiment of a rib retractor which spreads the ribs in a cephalad-caudal direction while simultaneously spreading the ribs in an anterior-posterior direction. However, like other examples from the prior art, there is no way to fine tune the opening, or to have one type of separation without the other, if desired, for a portion of the operation with this one retractor.
U.S. Pat. No. 6,416,468 discloses a rib retractor which can generate cephalad-caudal separation of the ribs, as well as an uneven amount of anterior-directed lift on the adjacent ribs. The '468 retractor has no opposing anterior-posterior rib movement. Furthermore, the '468 device employs a pivot point placed against the patient's body, somewhere in addition to the rib contact points, which can result in further bruising and discomfort.
Therefore, there is a need for a surgical rib retractor which can provide for varying and controlled amounts of rib separation in both a cephalad-caudal direction as well as an anterior-posterior direction without the need for external anchors or additional fulcrum points on the patient's body.
Surgical rib retractors may be used to displace or bend ribs in a variety of directions. Such displacement may cause certain ribs to fracture. Certain ribs are often surgically transected or even resected to provide for more rib displacement during retraction. Increased rib mobility enables further spreading of the adjacent soft tissue to provide greater access to the surgical site. If ribs unintentionally break during retraction, the fracture site may be suboptimal and have rough edges that may adversely affect healing. If one side (or plate) of a rib can remain intact while the other side is fractured, the intact area can act as a hinge while the opposing fracture site can provide for further bending of the rib during surgical retraction. The intact, hinged side of a rib can subsequently splint the opposing side of the fracture during healing. Bone fractures that occur on only one side of the bone, not through both sides, can occur from trauma (especially in the pediatric population with more supple bones) or are occasionally used in surgical procedures. This type of unilateral bony fracture is often referred to as a “green stick fracture” or a “green stick break.” This references the type of break that can be induced in young, fresh or green tree limbs during controlled bending. When a green stick break occurs or is caused in a rib, it has a potential to be less traumatic for the patient as compared to a complete break since the rib still has some strength and support intact. The location of such a break may impact the degree of morbidity a patient experiences. For example, it would be undesirable for a green stick break to occur too close to the junction between the rib cartilage and the adjacent rib bone in the rib cage. Therefore, it would be advantageous to have a device that can induce a green stick break at a desired location to enable more controlled rib retraction. Rib retraction usually occurs in the same plane as the ribs. To enable more aggressive anterior to posterior rib displacement during their surgical retraction, it may be advantageous to induce an anterior green stick fracture on the anterior side being displaced in the anterior direction and a posterior green stick fracture in the posterior side of the rib being pushed in the posterior direction.